Prius refurbishers that will buy my parts

You don't need a refurbished unit, just buy a used unit from anywhere that has one (junkyard). They don't fail often.

They don't want your old one because they don't really "refurbish" that type of part. They are just selling you a used unit

 

ZE3 warranty enhancement for the IPM covers you for 15 years unlimited mileage.

https://static.nhtsa.gov/odi/tsbs/2018/MC-10145758-9999.pdf

 

There have not been many reported failures on these, so it probably would be a safe purchase from a junkyard with a totaled/parted out vehicle. I don't think there's much demand so the prices should be fairly reasonable on this part

 

failed ipm's seem to come from repeated hard acceleration

 

the replacement solves the problem by reducing acceleration

 

Not always. Mine went out in a parking lot when powering up the car. Stone cold dead, required a tow. The real reason is a marginal design in early gen3s somewhat mitigated by the firmware update. Somewhat because many including mine had the update within days of availability (my sop), but the failure still occurred months later. The replacement hardware has effectively prevented repeat failures.

It is far easier to replace the whole inverter than it is to replace the problem board. But you don't get the better parts so its a compromise many accept. If you do go used, I would still pay the dealer to verify or install the software update.